The purpose of this work is to develop a new, very sensitive magnetic separation method for biological cells. The device can continuously separate cells in a static magnetic field on the basis of high gradient magnetic separation (HGMS). The separation is a closed, sterile continuous flow process, which will be applicable to clinical usage as well as for diagnostic purposes. The magnetic separation method can selectively separate target cells from a heterogeneous cell mixture suspension. The proposed continuous magnetic separator can simultaneously increase both grade and recovery of the target product unlike a conventional HGMS magnetic separator which captures all components together in the filter, resulting in a tradeoff between grade and recovery. The continuous magnetic separation method provides a unique apparatus that is very different in operating principle from existing techniques such as centrifugation and membrane ultrafiltration. The magnetic separation process is based on the magnetic susceptibilities of cells and is very gentle, minimizing or eliminating mechanical damage to the cells. The continuous magnetic separation method does not trap cells in the separator and does not require a wash-out cycle. It can minimize clotting, coagulation and aggregation problems of blood cells. Experimental evaluation of the continuous magnetic separation to be developed under this project will be performed by selective separations of white blood cells from whole blood and plasma separation. The goal of the two-year research project is to develop a highly sensitive continuous magnetic separation device for biological cells in a range of very weak magnetic susceptibilities (+10.6) and to evaluate selectivity and recovery performance of the separator using blood cells. A magnetic separator for future applications of various biological cell separations will be designed based on the use of a high-field superconducting magnet, taking into account the minimization of stray fields.